Police, who are continuing their investigation, have not yet identified a cause -- whether the phone or anything else.

In a statement received by CNN, Apple said: "We are deeply saddened to learn of this tragic incident and offer our condolences to the Ma family. We will fully investigate and cooperate with authorities in this matter."

Many have taken to to social media to question how the 23-year old from China's far-western Xinjiang Uygur Autonomous Region died.

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"(I) hope that Apple Inc. can give us an explanation. I also hope that all of you will refrain from using your mobile devices while charging," a person identified as Ma's sister posted on Weibo, China's Twitter-like service.

Meanwhile, Ma's father, Ma Guanghui, said that his daughter was electrocuted, adding that her body showed signs of electrocution, Xinhua said.

But Monday's Xinhua report also pointed out that mobile phones have a low output of only 3 to 5 volts, which isn't enough to harm the human body.